SYRINGE FOR MEDICINAL PURPOSES

Abstract: The syringe for medicinal purposes consists of a syringe barrel (1), one end of which is formed as an adapter (2) for a cannula or a closure (3), e.g., in the form of a tip cap, and of a plunger (4), arranged within the syringe barrel (1), and movable by a piston rod (5). At the end of the syringe barrel (1) facing away from the adapter (2), a plunger brake (6) is arranged, which is formed by a rest piece surrounding the syringe barrel (1) and connected removably to it. The rest piece has a projection extending into the lumen of the syringe barrel (1), which forms a stop for the side of the plunger (4) away from the adapter (2).

Description: Syringe for Medicinal Purposes The invention pertains to a syringe for medicinal pur¬ poses, with a syringe barrel, one end of which is desi¬ gned as an adapter for a cannula or a closure piece, e.g., in the form of a tip cap, and with a plunger ar¬ ranged in the syringe barrel and movable via a piston rod. Syringes of this type are increasingly being marketed, especially as ready-to-use syringes in prefilled form, for self-administration by the patient, as has long been the case, especially for regular administration of insulin in diabetics. In the case of unskilled or infirm people, there is a risk that before application the plunger will acciden¬ tally be pulled out of the syringe barrel so that, as a rule, the product is no longer usable. The invention has as its object the design of a syringe of the initially mentioned type in such a way that the plunger cannot get out of the barrel, or, if so, only with difficulty. This goal is achieved in accordance with the invention in that on the end of the syringe barrel, away from the adapter, a plunger brake is arranged, which is formed by a rest piece surrounding the syringe barrel and at¬ tached removably to it, which has a projection exten¬ ding into the lumen of the barrel, which forms a stop for the side of the plunger away from the adapter. The advantage achieved with the invention lies, first of all, in the fact that the projection extending into the lumen of the syringe barrel exerts a braking effect on the plunger, so that even in the case of incorrect manipulation of the syringe by the patient during use, so long as excessive force is not applied, the plunger cannot come out of the syringe barrel. Additional advantages arise in the course of manufactu¬ ring, since during the post-sterilization of solutions prefilled into the syringe barrel, the plunger is fre¬ quently forced out of the barrel by the pressure diffe¬ rences that arise. The use of the plunger brake pre¬ vents the plunger from being forced out of the barrel, for example, by an air bubble present in the barrel. In this process, the plunger brake can be sterilized along with the unit, if, for example, this is made of poly¬ propylene. As a result, the pharmaceutical safety of the syringe as a whole is increased. Since the plunger brake is placed removably on the syringe barrel, it can be removed from the syringe after use; disposal is sim¬ plified by separation of the different materials. In a first, advantageous embodiment of the invention, the rest piece is designed as an annular piece, and the projection is designed as fingers extending axially into the barrel, wherein the freely projecting end of the finger forms the stop for the plunger. In a preferred embodiment of the invention, the annular piece has a separation slit on the side opposite the finger. In this way, the annular piece can especially easily be clipped onto the barrel from the side. Advantageously, the annular piece is sleeve-shaped, so that it does not interfere with handling of the syrin¬ ge. For easier handling, the annular piece can be provided on its outer surface with a riffling travelling in the circumferential direction. This provides additional security when holding or handling the syringe. For this purpose, it can also be provided that the annular piece has two radially extending, diametrically opposite wings that form a finger rest. This is especially ad¬ vantageous when syringes with very small volumes are used. To achieve the best possible retention, the finger can advantageously lie against the inner wall of the syrin¬ ge barrel. In this way it is also ensured that the fin¬ ger will not interfere with actuation of the piston rod. In order to also be able to screw the piston rod with¬ out difficulty into the plunger, the invention also provides that the piston rod is tapered in the area adjacent to the piston rod thread provided for connec¬ tion to the plunger. In a second advantageous embodiment of the invention, which is provided for syringes in which the end of the syringe barrel away from the adapter has an annular projection extending radially outward, the rest piece is formed by a flat slip-on piece consisting of two disks separated by an interval, wherein the two disks are connected at the edges and between them, form a receiving pocket for the annular projection of the sy¬ ringe cylinder, open toward one edge, and wherein the disk away from the adapter is provided with a circular opening coaxial to the syringe barrel, the diameter of which is smaller than the internal diameter of the bar¬ rel, and the other disk has a recess, open toward the edge, for passage of the barrel. In this embodiment, the edge of the coaxial opening in the one disk forms the stopper for the plunger. This slide-on piece guarantees firm connection with the cy¬ linder and can also be designed such that it simultane¬ ously forms a finger rest. Since the piston rod extends through the opening into one disk, unintentional remo¬ val of the plunger brake is not possible, at least with the piston rod mounted in place. The recess advantageously has an edge shaped like the arc of a circle, coaxial with the circular opening, which surrounds the syringe barrel by somewhat more than 180 degrees and expands toward the edge of the disk. In this way, the slip-on piece can be connected simply and nevertheless firmly to the syringe barrel. To prevent the piston rod, once placed in the syringe barrel, from being able to be accidentally withdrawn, it is also provided that the wall of the circular ope¬ ning is designed as a cone mantle surface tapering to¬ ward the needle adapter, and the piston rod has on its end facing the plunger a radially outwardly projecting annular flange, the outer mantle surface of which like¬ wise tapers conically toward the stopper, wherein the opening and/or the annular flange is designed to be elastic, at least in its marginal area. It was found to be especially advantageous if the annu¬ lar flange is received in a form-fitting way by the circular opening. In the following, the invention will be explained in greater detail, based on exemplified embodiments shown in the drawings, which show: Fig. 1 a syringe in accordance with the invention in a first embodiment, in side view, with the plunger brake clipped on. Fig. 2 a perspective view of the plunger brake in ac¬ cordance with Fig. 1, Fig. 3 an additional embodiment of the plunger brake with syringe cylinder only partially represent¬ ed, in partial figure a before and in partial figure b after placement, in each case in per¬ spective view, Fig. 4 in partial figures a to d a plunger brake in cross section or top view, in each case shown with and without the syringe barrel, Fig. 5 an additional embodiment similar to Fig. 3, prior to insertion of the piston rod, and Fig. 6 the object in accordance with Fig. 5, but after insertion of the piston rod. The syringe for medicinal purposes shown in the drawing consists of a syringe barrel 1, one end of which is designed as an adapter 2 for a cannula or - as shown in Fig. 1 - for a closure piece 3 in the form of a tip cap. In the syringe barrel 1, a plunger 4 is arranged, which can be moved with the aid of a piston rod 5. At the end of the syringe barrel 1 away from the cannu¬ la adapter 2, a plunger brake 6 is arranged. The plung¬ er brake 6 consists, in detail, in a first embodiment shown in Figures 1 and 2, of a first annular piece 6.1, surrounding the barrel 1, and a finger 6.2 projecting into the interior of the barrel 1, connected to the annular piece 6.1. Here the free end of the finger 6.2 forms a stop for the plunger 4. The plunger brake 6 prevents the plunger 4 from being accidentally pulled out of the barrel 1 in the case of incorrect use of the syringe, for example by a un¬ skilled patient. Also, during the manufacturing process of prefilled, ready-to-use syringes, the plunger brake 6 prevents, for example, the plunger 4 from being forced out of the barrel 1 due to excess pressure occurring in the inte¬ rior during the post-sterilization of solutions previ¬ ously filled into the barrel 1. The annular portion 6.1 of the plunger brake 6, as shown in Fig. 2, consists of a separation slit 7 locat¬ ed on the side opposite the finger 6.2, as a result of which the plunger brake 6 can be clipped especially easily onto the syringe barrel 1 from the side. The annular portion 6.1 itself has an essentially sleeve¬ like shape, and is thus adapted in shape to the syringe barrel 1. To improve handling, the annular piece 6.1 can be pro¬ vided, in a way not shown in detail in the drawing, on its outer surface, with a riffling running in the cir¬ cumferential direction. In addition, or alternatively, as shown in Fig. 2, the annular piece 6.1 can be pro¬ vided with two radially extending, diametrically oppo¬ site wings 8, which form a finger rest. This is espe¬ cially advantageous in the case of barrels with rela¬ tively small volume, since these generally do not have finger rests. As Fig. 1 shows, the finger 6.2 lies against the inner wall of the syringe barrel 1, so that the piston rod 5 can be moved freely. The piston .rod 5 is tapered in the area 9 adjacent to the piston rod threads, so that the piston rod threads can be screwed into the plunger 4 without further ef- ford, even when the plunger brake 6 is clipped into place. In the additional embodiment of the invention shown in Figures 3 and 4, the rest piece is formed by a flat slip-on piece made up of two disks 10,11 positioned at a distance from one another. The two disks 10,11 are connected at the edge, and between themselves form a receiving pocket 12, open toward one edge, for the ra¬ dially outwardly extending edge of the syringe barrel 1. The disk 10 away from the adapter 2 is provided with a circular opening 13 coaxial with the syringe barrel 1, the diameter of which opening is smaller than the in¬ ternal diameter of the syringe barrel 1, so that the edge of this opening 15 (sic) forms the stop for the plunger 4. The other disk 11 has a recess 14, open to¬ ward the edge, for the syringe cylinder 1, so that this can be slid into the recess 14 from the side. As is especially recognizable in Fig. 4, the recess 14 has an edge that is coaxial to the opening 13 and is shaped like the arc of a circle, surrounding the sy¬ ringe barrel 1 by somewhat more than 180 degrees. In this way, firm retention of the slip-on piece on the syringe cylinder 1 is guaranteed. The recess 14 also broadens in the direction of the edge of the disk 11, simplifying the attachment of the slide-on piece to the syringe barrel 1. In addition, in order to prevent the piston rod from being able to be pulled out of the syringe barrel, the wall of the opening 13 - as shown in Figures 5 and 6 - is designed as a conical mantle surface tapering toward the adapter 2. The piston rod 5 has, at its end facing the plunger, a radially outwardly extending annular flange 15, the outer jacket surface of which likewise tapers conically, wherein the circular opening 13 and/ or the annular flange 15 are designed to be elastic, at least in the edge area. The dimensions are selected such that the annular flange 15 is received in a form-locking manner by the circular opening 13. In this way, to be sure, the pis¬ ton rod can be slid into the syringe barrel 1, wherein the two conical surfaces of the circular opening 13 and the annular flange 15 slip past one another, but cannot be pulled out again, as is clearly apparent from Fig. 6.

Claims: CLAIMS A syringe comprising an elongate hollow barrel having a distal end, an open proximal end and a chamber therebetween for retaining fluid, a tip at said distal end of said barrel having a passageway therethrough in fluid communication with said chamber, a plunger assembly including "a piston in slidable fluid tight engagement inside said barrel and an elongate plunger rod connected to said piston and extending proximally through said open end of said barrel, a plunger rod assembly brake removably attached to said open proximal end of said barrel including a rest piece housing portion partially surrounding and removably engaging said open proximal end of said barrel, a projection on said brake for engaging a complementary protrusion on said plunger rod assembly so that proximal movement of said plunger rod assembly with respect to said barrel will cause said brake projection and said complementary protrusion to engage and prevent removal of said plunger rod assembly from said barrel during normal use of said syringe. The syringe of claim 1 wherein said brake projec¬ tion includes at least one finger extending axial- ly into said chamber, said at least one finger including a distal end having an end surface for contacting said complementary protrusion of said plunger rod assembly to prevent removal of said plunger rod assembly from said barrel. 3. The syringe of claim 2 wherein said finger is in contacting relationship with said barrel in said chamber. 4. The syringe of claim 1 wherein said rest piece housing includes a circularly shaped side wall having an inside surface for contacting said bar¬ rel. 5. The syringe of claim 4 wherein said circularly shaped side wall includes a discontinuity of less than 180°. 6. The syringe of claim 5 wherein said discontinuity is on the opposite side of said brake from said projection. 7. The syringe of claim 1 wherein said rest piece housing portion is sleeve shaped. 8. The syringe of claim 1 wherein said plunger rod assembly brake includes a radially outwardly pro¬ jection wing, said wing forming a finger rest for applying axial force to said barrel. 9. The syringe of claim 1 wherein said complementary protrusion includes a disk-shaped structure on said plunger rod substantially perpendicular to a longitudinal axis of said plunger rod. 10. The syringe of claim 9 wherein said ' disk-shaped structure has a tapered frusto-conically shaped outside diameter. 11. The syringe of claim 1 wherein said barrel in¬ cludes a radially outwardly extending barrel pro¬ jection at said open proximal end, and said plun¬ ger rod assembly brake includes a planar element proximally spaced from said rest piece housing portion and connected to said rest piece housing portion to form a pocket containing said radially outwardly extending barrel projection, said planar element including an opening therethrough, said brake projection being formed in said opening. 12. The syringe of claim 11 wherein said opening is circular and said brake projection defines an in¬ side diameter smaller than the inside diameter of said barrel. 13. The syringe of claim 12 wherein said brake projec¬ tion defines a frusto-conically shaped inside dia¬ meter being smaller on the proximal side of said planar element than on said distal side of said planar element. 14. The syringe of claim 13 wherein said complementary protrusion on said plunger rod includes a disk- shaped structure substantially perpendicular to a longitudinal axis of said plunger rod. 15. The syringe of claim 14 wherein said disk-shaped structure has a tapered frusto-conically shaped outside diameter being larger on the proximal side of said disk than on said distal side of said disk.

Inventors: BITDINGER RALF, FRASCH EUGEN, OTTO THOMAS, VETTER HELMUT, BITDINGER, RALF, FRASCH, EUGEN, OTTO, THOMAS, VETTER, HELMUT
Applicants: BECTON DICKINSON CO, BITDINGER RALF, FRASCH EUGEN, OTTO THOMAS, VETTER HELMUT, BECTON DICKINSON AND COMPANY, BITDINGER, RALF, FRASCH, EUGEN, OTTO, THOMAS, VETTER, HELMUT
Application year: 1994
Main classification: A61M5
IPC codes: A61M5